This fiscal year we made substantial progress in characterizing the various neuronal populations of the PVT. For this purpose, we combined anatomical tracings, mouse genetics and viral vector methodologies, and identified three potential subclasses of PVT neurons. In particular, a subpopulation of PVT neurons that expresses dopamine D2 receptors, displays rapid increases in excitability following stress. Importantly, we have now unraveled a cellular and molecular mechanism underlying this stress-mediated increase in excitability. Furthermore, evidence collected by our group indicates that genetic disruption of this mechanism prevents the formation of a stress memory in the PVT. In summary, our observations highlight the presence of an unexpected circuit mechanism underlying the formation of stress memories. Scientific progress made during FY2017 at the Unit on the Neurobiology of Affective Memory, was marked by the incorporation of new technologies, such as fiber photometry. Using this technique in combination with genetically-encoded calcium and chloride sensors we were able to include in vivo assessment of stress circuits to our repertory of technical approaches. This new incorporation, together with other technological additions has significantly accelerated scientific progress in our laboratory.